A broad category of machines known as earthmoving machines are used in construction (and demolition) projects involving moving or removal of dirt and/or debris. As examples, self-loading scrapers, tractor dozers and the like are used in road construction and such dozers are used to dig basements for new buildings. And there are many other uses for such machines.
Briefly described, such machines move earth in much the same way that a wood plane shaves wood, i.e., by passing a blade across the earth surface and "rolling up" a layer of earth. Most such machines, which are hard-worked at least because they represent a very substantial investment, share a common feature. They have a blade with a main face plate (the curved plate forming most of the earth-pushing surface) and a relatively narrow, replaceable cutting edge mounted below the plate.
A replaceable cutting edge is desirable for many reasons. The entire blade is a relatively expensive repair component and the use of a replaceable edge greatly reduces the material cost of edge "renewal." It also reduces the labor cost since irrespective of the size of the blade (which can be several feet long and several feet high), a replacement cutting edge is much easier and quicker to handle than an entire replacement blade.
A type of known dozer blade with a replaceable cutting edge can, in certain earthmoving operations, be somewhat disadvantageous. One disadvantage relates to the fact that in the known blade, the lower edge of the face plate is "squared off" and presents an abutment-like surface on which dirt and other material "catches" as the layer of earth is removed.
Another disadvantage is that the front surface of the replaceable cutting edge is somewhat forward of the front surface of the main face plate. As a result, a "step" is formed between the main face plate and the upper part of the cutting edge.
Because of this step, dirt and other material does not discharge well from the blade. Rather, it "hangs up" on the step as the operator starts to raise the blade and move it away from the pile of dirt being pushed. To put it another way, the blade does not scour properly. And, of course, the more clay-like is the dirt being moved, the more likely it is that such dirt will catch in the step. This can be extremely annoying to the machine operator who expects that dirt moved to a pile will stay where placed as the machine moves away from the pile.
Another, less troublesome but nevertheless significant disadvantage is that to an experienced operator, the presence of the described step causes the machine and its blade to behave somewhat differently as dirt is being pushed. In other words, as the blade shaves or "planes" the earth surface, the machine exhibits a "feel" which is different (and less desirable) than that exhibited in the absence of such step.
This is a subjective perception not readily quantified--but there is little doubt about operator opinion in that regard. A paper titled "SHAPE OF DOZER BLADES TO ATTAIN SMALLEST FILLING RESISTANCE" (translated) discusses dozer blade configuration and performance and helps understand such perception.
A dozer blade with a replaceable cutting portion which overcomes the aforementioned disadvantages would be an important advance in the art.